Restricting the availability of paracetamol has reduced the number of tablets people take in an overdose attempt.

But reducing the paracetamol pack size has not has any impact on the number of people suffering serious harm after an overdose.

Researchers in Belfast found that people admitted to hospital with paracetamol poisoning since smaller packs were introduced in September 1998 had taken fewer tablets than before the change.

But selling paracetamol in packs with a maximum of 32 tablets does not seem to have cut the number of deaths or patients suffering severe liver damage as a result of an overdose.

Paracetamol is the most common drug used in overdose attempts, accounting for approximately 70,000 cases a year in the UK.

In the first six months of 1998 and 1999 similar numbers of patients - around 600 - were treated for paracetamol poisoning in Belfast hospitals.

Withdrawing the means isn't going to have any affect on those people who really want to commit suicide

The Samaritans

But the patients treated in 1999 had taken on average 20 per cent less paracetamol.

In 1998 two patients had to be transferred to a specialist liver unit but both recovered fully.

However, in 1999, three patients required specialist treatment with one needing a liver transplant and one patient dying.

First step

A spokesperson for the Samaritans said the reduction in paracetamol pack size had been a "valuable first step" but what is really needed is help to deal with the underlying problems of isolation and despair.

"Withdrawing the means isn't going to have any affect on those people who really want to commit suicide," she told BBC News Online.

"The change in pack sizes is an admirable initiative but we really need to encourage an environment where people who have suicidal feelings can talk to those around them."

And, the authors of the report, published in the British Medical Journal acknowledged that "the only benefit we noted was a reduction in costs because fewer antidotes were given and there were fewer hospital admissions."